LOS ANGELES, Calif. (FOX 11 / CNS) - With Southland temperatures pushing into the sizzling range, a red flag warning signifying a wildfire threat will be in force until Monday afternoon in Los Angeles County mountains and valleys because of strong wind gusts, high heat, low humidity and extremely dry vegetation.
The warning will be in force until 3 p.m. in the San Fernando, Santa Clarita and San Gabriel valleys, both the San Gabriel and Santa Monica Mountains and the Angeles National Forest -- but not the Antelope Valley. Red flag warnings are also in force in Ventura County.
The warning had also been in place for the Los Angeles County coastal area, which stretches inland to downtown Los Angeles, but National Weather Service forecasters canceled it, citing shifting winds.
"Due to an easterly shift and slight weakening of the winds today, the Los Angeles County coasts should not expect much wind and have been removed from the red flag warnings,'' according to the NWS. "All other areas will remain in effect, though with slightly weaker winds than Sunday.''
Winds will blow through the warning areas at between 15 and 30 mph, gusting to 45 mph, according to the National Weather Service, which described the winds sweeping the region since late last week as the first significant Santa Ana wind event of the season. At the same time, the humidity level will be between 5 and 15 percent, and the vegetation will remain bone dry, representing highly flammable fuel if fire breaks out, forecasters said.
Temperatures, meanwhile, were already soaring by midday. In downtown Los Angeles, the temperature at noon was 100 degrees -- 5 degrees warmer than the usually much hotter desert city of Palm Springs.
Los Angeles International Airport, Long Beach, Fullerton, Hawthorne, Santa Ana, Woodland Hills and Torrance all hit the triple-digits by noon, according to the NWS, and many other cities were hovering in the high 90s.
The heat was even affecting train service in the area. Metro imposed speed restrictions on some of its light-rail lines to prevent possible damage to tracks or wires. Passengers were advised to expect possible delays on the Metro Gold, Blue and Green lines -- but not the more coastal Expo Line.
The doors on the trains were also put on ``passenger release mode,'' meaning they will not open automatically. Passengers must press a button adjacent to the doors to open them. The move is aimed at preventing doors from opening unnecessarily at stations, allowing hot air into the air-conditioned trains.
Temperatures will decrease Tuesday -- by as little as 3 degrees in some communities and by as much as 9 degrees in others -- and fall again progressively over the ensuing days. By Sunday, downtown is forecast to have a high of 79, 21 degrees lower than today, and Woodland Hills will top out at 83, or 22 degrees less than today's high.
In Orange County, where a heat advisory will be in force until 8 tonight, the NWS forecast sunny skies and highs of 91 in Newport Beach and Laguna Beach; 92 in San Clemente; 101 in Anaheim, Mission Viejo and Fullerton; 102 in Yorba Linda; and 103 in Irvine.
A steady cooling trend will begin Tuesday. Along the coast, Newport Beach will go from 91 today to 73 Sunday. Inland, Irvine will go from 103 to 78.
Copyright 2016 FOX 11 Los Angeles: Download our mobile app for breaking news alerts or to watch FOX 11 News | Follow us on Facebook, Twitter, Instagram, and YouTube. Be a citizen journalist for FOX 11 and get paid - download the Fresco News App today.